Organizations seeking tax-exempt status used to have to go through a two step process in which they first received an advance ruling allowing them to operate as a public charity for 5 years, and then had to demonstrate that they received a substantial portion of their support from public sources in order to receive a final determination letter. However, the revised From 990, the tax return which organizations exempt from federal income tax must file, has eliminated the need for this two step process.
Those organizations which received an advance ruling but have not yet received a final determination letter will no longer need to do so. Instead, they will be allowed to use their advance ruling letter as their final determination letter.
For more information, see the IRS's website.